Sugar, or sucrose, is probably the most important ingredient in the confectionery industry. Sucrose is used to provide both the sweetness and the body in confectionery products and its properties also govern the textural attributes of such products. Although a wide variety of alternative sweeteners are commercially available, it is generally considered that sucrose is the optimum sweetener with regard to taste profile and technological properties. However, sucrose has been implicated as a contributory factor in many diseases, including hypertension, coronary heart disease, arterial sclerosis and dental caries. These health concerns have led health care professionals to analyze the effects of sucrose and its prominent role in the diet.
Perhaps the most significant, well-documented effect of sucrose is its contribution to tooth decay. The mouth contains a number of bacterial strains, principally Streptococcus mutans, which ferment common dietary carbohydrates such as sucrose. This fermentation generates acid as an end product which lowers the pH in the mouth; the lowered pH leads to a demineralization of tooth enamel and finally to the formation of dental lesions or caries.
The presence of sucrose and other fermentable carbohydrates in regular meals is not the principal cause of tooth decay; the consumption of between meal snacks which contain high concentrations of sucrose, such as confections, has been shown to have a close relationship to the formation of dental caries. Long after the confection has been consumed, sucrose stays in the mouth and is fermented by S. mutans and other bacteria, lowering the mouth pH and promoting dental caries as described above.
One approach to fighting dental caries is to reduce or eliminate the amount of fermentable carbohydrates such as sucrose in confections and other snacks. The replacement of fermentable carbohydrates by sugar substitutes which cannot be fermented, or are less easily fermented by S. mutans and other bacteria has been shown to decrease the development of dental caries.
The quest for adequate sugar substitutes in this context has not, to date, been completely successful. Generally speaking, confections can be made using sugar substitutes but sugar substitutes do not often provide the same desirable taste and textural qualities that sucrose does. Most sugar substitutes, such as "bulk" sweeteners like sorbitol, mannitol, isomalt, lactitol, maltitol and hydrogenated glucose syrup are not as sweet as sugar and unless combined with other sweeteners, do not provide sufficient sweetness and/or acceptable taste. Confections made with sugar substitutes may be sweetened (in whole or in part) with intense artificial sweeteners such as dipeptide sweeteners (including aspartame), acesulfame K, saccharin and cyclamates. Intense sweeteners have at least two drawbacks: although they are far sweeter than sucrose and sugar substitutes, they often impart an unpleasant aftertaste and they do not contribute any of the body or bulk necessary for an acceptable product.
Xylitol has been used as a sugar substitute in certain contexts, including chewing gum. For example, U.S. Pat. No. 4,514,422 (Yang) and 3,422,184 (Patel) disclose the use of xylitol (as well as other sugar alcohols) in sugar-free chewing gums. To date, however, xylitol has not been effectively and commercially utilized to sweeten cooked, reduced calorie or "lite" confectionery products such as hard candies, chewy candies and gelatin jelly candies. In these contexts, xylitol, because of certain characteristics such as its low viscosity and unique crystallization properties, has been difficult to integrate into a shelf stable, acceptable tasting product which can be efficiently and practically produced on a commercial scale. In addition, although xylitol has been used to sweeten full calorie chocolate confections, in this context, xylitol exhibits an unpleasant "burning" aftertaste. Finally, because xylitol has the same caloric value as sugar its use in dietary products with reduced calories has been limited. The Federal Drug Administration has defined a "reduced calorie" food as one which has at least one third less calories than standard food products.
Our invention, however, provides for a sweetening composition which includes xylitol which is particularly suitable for use in hard candies, chewy candies, gelatin jelly candies and other applications such as chocolate confections and praline or fondants. Because of xylitol's low viscosity, certain confections utilizing it are subject to cold flow and are often unstable within a few days of production. The present invention utilizes a combination of xylitol and a reduced calorie bulking agent which unexpectedly results in a shelf stable product which is not subject to cold flow. The present invention can also include an additional polyhydric alcohol and/or an intense sweetener if necessary to add needed sweetness.
Further, it has also been unexpectedly discovered that the use of xylitol per se in some contexts as a sweetener imparts sufficient sweetness even when it is not substituted for sugar in a one-to-one ratio. Hence, in combination with a reduced calorie bulking agent, the present invention comprises a dietetic sweetening composition with reduced calories in the absence of any intense sweetener, a product not thought possible in view of the caloric equivalence of sucrose and xylitol.
Confections sweetened with xylitol are particularly desirable because of the known advantages of xylitol. Xylitol is a naturally occurring five carbon sugar alcohol which has the same sweetness and caloric content of sugar (4 kilocalories per gram). Xylitol is found in small amounts in many fruits and vegetables and is produced in the human body during normal metabolism. Xylitol is particularly attractive because of its known metabolic, dental and technical characteristics.
From a metabolic perspective, xylitol is metabolized largely independent of insulin, so it can be safely consumed by non-insulin dependent diabetics. Further, xylitol has been shown to delay gastric emptying and to possibly suppress food intake which means it may have an important role in weight reducing diets.
A significant advantage of xylitol is that it is not fermented by S. mutans and other bacteria found in the mouth and, therefore, does not produce acids which, as described herein, contribute to the formation of dental caries. Xylitol is well established as a non-cariogenic substance, i.e. xylitol does not contribute to caries formation. Significant data also exists which supports the view that xylitol is not only non-cariogenic, but actively suppresses the formation of new caries and may even reverse existing lesions by inducing remineralization, i.e. it is a cariostatic material. A summary of clinical data regarding the effects of xylitol and its possible mechanisms is set forth in Bar, Albert, Caries Prevention With Xylitol: A Review of the Scientific Evidence. 55 Wld. Rev. Nutr. Diet. 183-209 (1983). The mechanism or mechanisms by which xylitol effects any cariostatic properties is not yet known, but some possible mechanisms which have been suggested include a reduction of oral levels of S. mutans, a lack of contribution to the growth of plaque bacteria, the stimulation of the flow of protective saliva, the favorable alteration of the composition of saliva, the retardation of demineralization and an enhancement of remineralization of tooth enamel.
Xylitol also has significant technological advantages, particularly with respect to taste profile. Xylitol produces a pleasant cooling effect in the mouth when consumed in the crystalline state. The energy required to dissolve one gram of xylitol is 34.8 calories, the highest known value for sugars and sugar alcohols; this produces a physical cooling effect which is desirable in many contexts. Xylitol is as sweet as sugar and does not typically manifest unpleasant aftertastes.
The present invention also discloses a novel method for producing a shelf stable, reduced calorie sugar free chewy candy which contains xylitol. The method, in which a candy mass is allowed to sit for a period of about 12 hours (e.g. overnight) and then worked by means of a high speed mixer or suitable expedient to disrupt the crystalline structure, permits higher quantities of xylitol fondant to be utilized without a reduction in stability.
In a further method aspect, xylitol is used to regulate the viscosity in cooked hard candy masses to allow the inclusion and homogenous dispersion of an intense sweetener. Reduced calorie bulking agents--such as polymers of glucose and maltose--are known to create a mass of such viscosity when boiled that intense sweeteners cannot be adequately added and dispersed throughout the mass. Xylitol acts to lower the viscosity of the mass--to an extent greater than that predicted theoretically--to the point where an intense sweetener can be added and dispersed. Although some of the polyols may have a similar effect, they are not as effective as xylitol and do not have the sweetness or crystallization properties of xylitol.